Conventional cleansing compositions such as shampoos, for example, contain standard surfactants such as anionic, nonionic and/or amphoteric type surfactants in amounts such that the resulting composition display either liquid or solid rheological behaviors, but not both. Typically such compositions exhibit Newtonian or viscoelastic behavior. Those compositions that exhibit viscoelastic behavior are mostly dominated by liquid behavior within the frequency range 0.1 to 50 rad/s. Solid behavior only becomes dominant at frequencies higher than 50 rad/s and therefore it is not noticeable macroscopically (e.g. by a consumer) under typical usage conditions (e.g. squeezed through the bottle or rubbing between hands).
Conventional shampoos that exhibit gel-like, elastic behaviors typically use structuring agents (also known as thickeners or rheology modifiers) such as saccharides, gums, guars, cellulose derivatives and high molecular weight thickening polymers. See, for example, US Pub. 2004/0097385, U.S. Pat. No. 6,770,607, and U.S. Pat. No. 5,965,502. These materials are known to thicken compositions by building an associative network with other ingredients in the composition (mainly anionic surfactants) resulting in the elastic/solid-like behavior discussed in the foregoing publications. In contrast, the inventive compositions herein disclosed yield cleansing gels that exhibit solid like behavior without the use of rheology modifiers and/or thickeners. It is advantages to avoid such rheology modifiers and thickeners as these materials are known to impact negatively usage qualities of cleansing compositions, such as for example, resulting in slower flash foam, lower overall foam level, lower potential for delivery of actives or conditioning agents, poor distribution during application and slower “break” of the compositions.
The compositions of the invention display liquid behaviors when slowly deformed (e.g. flow freely when the holding container is tilted) and solid, gel-like behaviors when quickly deformed (e.g. touched, sheared or squeezed through and orifice or nozzle). Furthermore these cleansing compositions have Newtonian behavior (that is, nearly ideal liquid behavior) within the range of frequencies where the liquid behavior is dominant and near ideal elastic behavior within the frequency range where the solid behavior is dominant. The compositions of the invention are thus useful in multiple applications of cleaning compositions.